Walking TCU's

I was just reading the outdoor gear lab review on cams, and noticed they include "walking" as a con of each one of the TCU's reviewed. I understand walking is an issue with all cams if the conditions are such to make it happen, but is it particularly an issue for the TCU or have you all had different experiences with them? And if they do tend walk more, does any particular make/model walk less than the others? Curious about this because I was thinking about adding a few to my rack.

Theoretically speaking a "TCU" or Three Cam Unit will walk less because only two lobes will advance as the cam rotates around the third (widest) in each movement parallel to the crack. A traditional four cam unit will advance three lobes around the fourth lobe. This, combined with the fact that TCUs are inherently narrower than traditional cams means that each movement parallel to the crack affects the cam less.

However, TCUs require more experience to properly place and are more sensitive to abnormalities in the rock. This means that practically speaking TCUs are more likely to experience placement compromise than traditional cams.

Great explanation. Thank you. Not sure why outdoor gear lab wanted to make it an issue. But I guess any gear review is subjective and based on how the product is being used.

Jon Kulikowski wrote:Theoretically speaking a "TCU" or Three Cam Unit will walk less because only two lobes will advance as the cam rotates around the third (widest) in each movement parallel to the crack. A traditional four cam unit will advance three lobes around the fourth lobe. This, combined with the fact that TCUs are inherently narrower than traditional cams means that each movement parallel to the crack affects the cam less. However, TCUs require more experience to properly place and are more sensitive to abnormalities in the rock. This means that practically speaking TCUs are more likely to experience placement compromise than traditional cams.

In my experience, it is exactly the opposite. 3 cam units walk more easily than a four cam unit. The central cam essentially acts as a pivot point. As the cam is moved back and forth by the rope pulling on the sling, the cam will rotate around this central pivot point, allowing the outer cams to walk further into the crack. Four cam units need to move both central cams and this is more difficult. Prove it to yourself. Take a Metolius TCU and a 4 cam unit and place them in a parallel crack. Wiggle them up and down a little and watch the TCU walk into the crack more easily.

csproul wrote: In my experience, it is exactly the opposite. 3 cam units walk more easily than a four cam unit. The central cam essentially acts as a pivot point. As the cam is moved back and forth by the rope pulling on the sling, the cam will rotate around this central pivot point, allowing the outer cams to walk further into the crack. Four cam units need to move both central cams and this is more difficult. Prove it to yourself. Take a Metolius TCU and a 4 cam unit and place them in a parallel crack. Wiggle them up and down a little and watch the TCU walk into the crack more easily.

^^^ this.

Notice also that a lot of popular TCU's have stiffer stems compared to 4-lobe designs.

csproul wrote: In my experience, it is exactly the opposite. 3 cam units walk more easily than a four cam unit. The central cam essentially acts as a pivot point. As the cam is moved back and forth by the rope pulling on the sling, the cam will rotate around this central pivot point, allowing the outer cams to walk further into the crack. Four cam units need to move both central cams and this is more difficult. Prove it to yourself. Take a Metolius TCU and a 4 cam unit and place them in a parallel crack. Wiggle them up and down a little and watch the TCU walk into the crack more easily.

Yup. This fits with my experience.

HUH... I also found that 3 cams pivot rather than walk..I believe because of the center cam being wider...just my experience

In my experience metolius TCUs walk a lot more than single stem flexible cams like aliens. Way more.

They have a fairly rigid stem and will pivot/move very easily with any tug on the rope. As they pivot/move back and forth they're much more prone to ending up in a bad position with lobes open. They might not 'walk' and move very far, but they move enough to possibly compromise the placement. If the crack is perfectly uniform this might not be as much of an issue, but most cracks don't fit this description.

A flexible cam like an alien is much more likely to remain in the exact position that you placed it in. I find this to be a very valuable asset.

Sure, you can sling all of your cams to mitigate this, but this isn't always possible or necessary. But even in a straight up/down crack the simple act of climbing past the piece can make it move enough to change its original position. I find personally that more flexible cams do this much less.

TCUs are fine units and plenty of people swear by them. They've been around forever. I just prefer aliens (for this reason and a number of others - softer metal seems to bite granite better, narrower heads, more camming range).

The tcus rotate more than 4 lobe cams ... The good news is that in a fall they can also rotate back into the fall line more easily than a 4 lobe cam that shifts

However they do tend to "walk" a bit more (rotate really) due to the pivot on the centre lobe and the stiffer stems

The bd c3s have the same issue as well as the dmm 3 cu

Its really a cr@pshoot to say which is better as a 4 lobe cam that shift may not rotate as easily back in the direction of the fall and be forced into a perpendicular placement where it may fail ... The infamous 3 blown out x4 thread (and one additional blown out one by another experience climber) there was some speculation that once those 4 lobe cams walked they got stuck in a perpendicular placement as they dont rotate as easily and thus pulled

I own a few TCUs and powercams ... And many 4 lobe microcams ...

And the blue TCU is one of my goto pieces that i place often, its seen quite a few whippers

My other favorite is the green alien

Any of these cams will work if you know their limitations and use them right

Despite the marketing propoganda from some manufacturers and "reviewers" (im looking at you climbing mags and blog sites) there is no such thing as the perfect microcam ... Every one has advantages and limitations, its all a matter of tradeoffs

;)

I own mastercams and aliens. Plenty of partners have TCUs and honestly they work fine too. With microcams there will always be edge cases (e.g. a mastercam fits where an alien won't because it's narrower, a TCU fits in a strange pod better than a 4 cam unit due to its shape, etc.)

As to walking, TCUs personally I think might be slightly more prone, but in 90% of placements it will be a wash.

At the end of the day, I find that having a variety is nice.

Bearbreeder said:

"Any of these cams will work if you know their limitations and use them right.

Despite the marketing propoganda from some manufacturers and "reviewers" (im looking at you climbing mags and blog sites) there is no such thing as the perfect microcam ... Every one has advantages and limitations, its all a matter of tradeoffs."

Truer words have never been spoken. End of discussion.